The proposed study will evaluate the quality of external beam radiotherapy for clinically localized prostate cancer and relate variation observed to event-free survival and post-therapy morbidity. Among men with clinically localized disease, studies have documented racial and socioeconomic disparities in mortality and morbidity outcomes. We address the question of whether variation in the quality of radiotherapy may explain a portion of the observed disparities. The data source for this research will be the linked Surveillance, Epidemiology and End Results (SEER)-Medicare database. In Specific Aim 1, we will characterize variation in the quality of radiotherapy and its relation to patient demographic and clinical characteristics and access to care. In Specific Aim 2, we will examine the relation between radiotherapy quality and event-free survival and post-therapy morbidity. We hypothesize that variation exists in adherence to radiotherapy quality measures and that patient factors like non-Hispanic white race and higher socioeconomic status may predict for receipt of higher quality radiotherapy. Furthermore, we hypothesize that higher radiotherapy quality performance is associated with longer event-free survival and lower morbidity. [unreadable] [unreadable] [unreadable]